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Dynamically change log level after init #228
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I'd like to mention that I have a similar use case. I have tried to disable logging before initializing the builder but it doesn't work. I've also tried to send all the log to a sink target, but it doesn't work either. It seems that the RUST_LOG env. variable takes priority over the settings of the builder...
This is what I do:
log_builder.filter(None, LevelFilter::Error); log_builder.target(env_logger::Target::Pipe(sink)); log_builder.init();You don't need
env_loggerto change the log level as the log crate already provideslog::set_max_level.You don't need
env_loggerto change the log level as the log crate already provideslog::set_max_level.the documentation says
Generally, this should only be called by the active logging implementation., isenv_loggerfine with it being change outside of itself?I think you might get strange results calling
set_max_leveldirectly, sinceenv_logger"compiles" the max level into its filters, those aren't derived on-the-fly from the max level set inlog.Reacted by Kevin Yue- added 2 commits that reference this issue
on Oct 14, 2024 Below is what I implemented using the
log-reloadcrate. Works perfectly.logger.rs
use std::sync::OnceLock; use env_logger::Logger; use log::{warn, Level}; use log_reload::{ReloadHandle, ReloadLog}; static LOG_HANDLE: OnceLock<ReloadHandle<log_reload::LevelFilter<Logger>>> = OnceLock::new(); pub fn set_max_level(level: Level) -> anyhow::Result<()> { let log_handle = LOG_HANDLE.get_or_init(|| { // Initialize the env_logger and global max level to trace, the logs will be // filtered by the level_filter_logger below let logger = env_logger::builder().filter_level(log::LevelFilter::Trace).build(); log::set_max_level(log::LevelFilter::Trace); // Create a new logger that will filter the logs based on the max level let level_filter_logger = log_reload::LevelFilter::new(level, logger); let reload_log = ReloadLog::new(level_filter_logger); let handle = reload_log.handle(); // Register the logger to be used by the log crate if let Err(err) = log::set_boxed_logger(Box::new(reload_log)) { warn!("Failed to set the logger: {}", err); } handle }); // Update the log level log_handle .modify(|logger| logger.set_level(level)) .map_err(|e| anyhow::anyhow!(e)) }
Call
logger.set_max_level(level)dynamically to change the log level at runtime.Reacted by Robert Jacobson
Is there currently a way to change the log level after having called
initalready? If there is currently no way, i would like to request this featureUse case:
i would like to enable logging as the first thing in my code to have log output (from env, etc) and later after having parsed the cli (like with clap) set the level based on something like
verbosity.also another use case would be to dynamically turn the logging on / off for a specific part (which is probably already covered by #144)